1) Field of the Invention
This invention relates generally to fabrication of polysilicon resistors for semiconductor devices and particularly to the fabrication of a resistor with both p-type and N-type doping and more particularly to an On-chip temperature controller having polysilicon load resistors that have both p-type and N-type doping by a ion co-implant process.
2) Description of the Prior Art
As the device dimensions decrease and the packing density increases, the power dispassion becomes a major consideration in circuit operation. In the future, the on-chip temperature sensor to detect and control temperature variation will become more important.
For the traditional power transistor, the large current flow and high operation voltage will also increase temperature rapidly, which can damage the power device and decrease the lifetime of the circuit. It important that the resistor have a low temperature coefficient (i.e., low change in resistivity with temperature change).
The importance of overcoming the various deficiencies noted above is evidenced by the extensive technological development directed to the subject, as documented by the relevant patent and technical literature. The closest and apparently more relevant technical developments in the patent literature can be gleaned by considering U.S. Pat. No. 4,298,401 (Nuez) that shows a breakdown voltage resistor obtained through a double ion-implantation (Both same conductivity resistor) into a semiconductor substrate.
U.S. Pat. No. 4,762,801 (Kapoor) shows an amorphous poly resistor and I/I an impurity to give the resistor the proper Temp coefficients.
U.S. Pat. No. 5,037,766 (Wang) shows a poly resistor treated with an Oxygen treatment.
U.S. Pat. No. 5,489,547 (Erdeljac) shows a method of fabricating semiconductor device having polysilicon resistor with low temperature coefficient.
However, the temperature coefficient's of poly load resistors can be further improved.